For many years musicians have appreciated the sound producing ability of older wooden instruments such as guitars and violins. It is known by those skilled in the art that new wooden musical instruments do not sound as good as properly maintained and regularly played instruments that are several years old. Further, a good sounding wooden musical instrument that has not been regularly played experiences a noticeable degradation in sound quality over a period of several years.
There have been many attempts to artificially age an instrument to improve its sound producing quality. One method reputed to be in commercial use in Germany involves placing an electric guitar in front of loudspeakers in an enclosed room and subjecting the instrument to loud music emitted from said loudspeakers.
Ashworth U.S. Pat. No. 5,031,501 discloses attaching a transducer to the sound board of a stringed instrument such as a guitar or violin and applies an amplified musical signal to the transducer to thereby simulate what the sound board experiences as the instrument is being played. Ashworth's invention provides automatic means to simulate playing the instrument, thus allowing the instrument to be aged without the expenditure of any time or effort by a real musician. However, it will still take a prolonged period of time to age a new instrument using Ashworth's method because his invention merely facilitates "playing" the instrument of an increased amount of time, and is not suitable for subjecting an instrument to the effects of many years of use.
Additionally, some instruments inherently have "dead" and/or "hot" spots. With these instruments the sound producing ability of the instrument is uneven over its range. There are no known methods for curing these sound producing anomalies without physically repairing the instrument or dramatically altering some of the parts of the instrument.
Electrodynamic vibration shakers are typically used in the aerospace industry to verify whether a piece of hardware meets a particular military or commercial specification for resistance to vibration. The simplest shakers are controlled by a single frequency sinusoidal signal, which results in the shaker, and any piece of equipment supported by the shaker, to be subjected to a sinusoidal motion. More recently, shakers have been developed which are controlled by a broad spectrum signal, which produces vibration simultaneously and randomly over a broad spectrum of frequencies. The vibration produced by such broad spectrum shakers is typically measured in units of acceleration (g rms), and may be represented in graphic form as the power spectrum density (g.sup.2 /Hz). Although sophisticated digitally controlled vibration testing and related measuring techniques have been used to analyze the acoustic response of a musical instrument such as a Stradivarius violin, such tests have used relatively low amplitude vibrations applied for a relatively short period of time and there have been no reports of any noticeable change in sound quality as a result of such testing.
From the above, it may be appreciated that the prior art lacks any suggestion of a relatively simple and quick method for making a new instrument produce the sound quality heretofore associated only with older instruments, for restoring the sound producing quality of an instrument that has been unplayed for many years and for correcting anomalies in the sound production of an instrument having "dead" or "hot" spots in its useful range.